The present invention relates to a mechanical stamping press with variable speed slider-crank mechanism driven by a servomotor which can be used for various types of press work.
In the development of industrial technology continuous efforts are being made to enhance production precision for quality requirements. Many products which are widely used in industry presently are formed by cutting, forging, stretching, bending, and pressing processes. These manufacturing processes are achieved by means of a press.
Generally speaking, when the punch of the press starts to touch the work-piece during the cutting process, noise is accompanied with the impact and the life cycle of the tooling is also shortened. Therefore, low-speed cutting process is preferred. Also, in order to obtain a fine cutting edge, and protect the press machine and tooling from excessive wear, it is better to make fine cuts at low speed. In addition, in stretching process, the stretching speed should not be fast and should be within a maximum allowable stretching speed to avoid work-piece fracture. Furthermore, in order to get good work-piece quality, constant stretching speed in the working region is required.
Traditionally, the mechanical press has different kinds of driving mechanism depending on the type of process for which it is used. However, the only driving mechanism which is usually used in both cutting and stretching is the Watt II type linkage mechanism press. The Watt II type linkage press is shown in FIG. 1 and the AMADA-150L Watt II type linkage press is shown in FIG. 2. These presses cannot obtain a good finished quality because the ram of the presses doesn""t operate at constant speed in working region. W. M. Hwang el. proposed a common linkage type of press in Taiwan Patent No. 248,739 for both stretching and cutting processes. However, the two processes are inherently different so that the Hwang el. solution is a compromise between the said processes rather than a satisfaction of both of them. In Int. J. Mach Tools Manufact., Vol. 31, No. 3, pp. 349-359, Yossifon et al.(1991) a new type of multi-function press driven by servomotor is proposed. A nut-screw mechanism is used to transfer circular motion from the servomotor to linear motion, which is then used to drive the sliding platform. However, due to lack of high mechanical advantage which the linkage-type press often possesses, the servomotor needs to provide high torque for smooth operation. U.S. Pat. No. 5,079,489 xe2x80x9cMethod of operating press machine and servo controller thereforxe2x80x9d issued at Jan. 7, 1992 has claimed the similar concept of using a servomotor and its control system to control the press ram. However, what it does not mention is the proposal of using the combination of a servomotor, controller, and crank-slide linkage mechanism. Such a combination can offer a suitable speed function in different types of processes to control the servomotor.
Based on the above, the present invention provides one kind of software-controlled servo press mechanism. This results in the input speed of the servomotor which can be controlled by software, so that the motor can run in different speed functions during the cutting and stretching processes. Therefore, this mechanism can achieve the optimal processing effect in the two types of processes.
The main object of this invention is to provide a common and multi-function crank-slide type press (system) with variable-speed servo controller. The system offers different input speed for different types of punching processes, which achieves the purpose of using a single press for different types of working processes.
Another object of this invention is to provide this common and multi-function crank-slide type press (system) with variable speed servo controller which can be applied to traditional mechanical press; this is namely a traditional press upgrade.